共查询到20条相似文献，搜索用时 31 毫秒
1.
R. K. Srivastava 《Astrophysics and Space Science》1987,129(1):143-147
A new period (P=3d.687664) of the eclipsing binary system IZ Persei is given, based on 16 observed times of the minima. O–C diagrams of IZ Per have been presented for the first time, and the period variations have been estimated in different portions of the O–C diagram. Significant period changes do not appear to have occurred in IZ Per. The O–C diagrams suggest that the period of the system is continuously increasing at a rate of 25s yr–1. Period variations of the order of 10–5 d appear to have occurred around the years 1969, 1972, and 1978. The period increases are stronger than the period decreases; but these are yet to be confirmed. The overall picture of IZ Per suggests that strong period changes are not present in the system; however, slow increase of period is apparent in IZ Per. The total period change (3×10–6 d) till the last epoch is in agreement with the newly derived period of IZ Per. 相似文献
2.
The results of photoelectricUBV observations of asteroid 77 Frigga during the 1982 opposition are presented. From eight nights of observations at phase angles smaller than 2
o
.
8 a synodic period of 0
d
.
3755±0
d
.
0006 is derived. The light curve appears very symmetric with two maxima per period and an amplitude of 0
m
.
19. The primary maximum corresponds toV(0o)=8
m
.
58, and the colour indices are:B–V = 0
.
m
738 ± 0
.
m
003 andU–B = 0
.
m
200 ± 0
.
m
002. 相似文献
3.
Ram Sagar 《Astrophysics and Space Science》1976,40(2):447-454
The results of photoelectricU, B, V photometry of the galactic cluster NGC 2169 are presented. The colour excessE(B-V) is 0m.18. The distance modulus to the cluster and its age are respectively estimated at 9m.6 and 0.9×107 yr. Star No. 10 is found to be variable. 相似文献
4.
The H-R diagram of the open cluster Tr-1 based on Oja-membership andU, B, V photoelectric photometry is presented. The colour excessE(B-V) is 0
.
m
52. The distance modulus to the cluster and its age are, respectively, estimated at 11
.
m
6 and 2.6×107 yr. 相似文献
5.
UBV photoelectric observations of the W UMa-type binary V471 Cas were made from September to November 1984. Its colour indices were found to be(B-V)=0
.
m
771±0
.
m
02 and(U-B)=0
.
m
196±0
.
m
02. TheU, B, andV light curves of V471 Cas show some photometric fluctuations. We found that its orbital period is not 0.335998 days which was given by GCVS (1986), but 0.405356 days.Photometric orbital elements of V471 Cas were found using the Wilson-Devinney method. V471 Cas is a contact system, in which the overcontact factor is 0.19, its mass ratio of two components is 0.5947, and orbital minclination is in 83.29 degrees. 相似文献
6.
UBV photometry of RS CVn-type eclipsing binary system ER Vulpeculae has been presented. The period comes out to be 0
.
d
698093. The average depths of primary and secondary minima are, respectively, 0
.
m
21 and 0
.
m
12. The colours at various phases have been given. A dip is seen around phase 0
.
p
73 as was seen in the observations of Arevaloet al. (1988). Large scatter is present in the observations as noticed earlier, and may be due to activity of the components. 相似文献
7.
Photoelectric observations of WX Eridani inB andV filters have been discussed. The maximum magnitudes of the system areB=9
m
.70 andV=9
m
.46. TheB-V colours of the components are 0
m
.16 and 0
m
.80 for the primary and the secondary, respectively, while their spectral types are A5+K0. The period has been found to be constant and its revised value is 0d.823 270 76. 相似文献
8.
A comparison between model atmosphere grids with and without metal blanketing has been performed in the low-temperature range (T
eff=6000 K to 10000 K) and for different metal contents (logA=0, –1, –2;A=scaled solar abundance). ForA10–1 andT
eff7000 K, the Johnson colour indicesU-B andB-V, together with the Strömgrenu-b, b-y and the bolometric correction (BC) are little affected by metal blanketing ( mag<0
.
m
04). On the other hand, the trend of the physical quantities and them
1 andc
1 colour indices reflect the inadequateness of the models even withA=10–2 andT
eff=9500 K, where hydrogen line blanketing is expected to dominate. This fact discourages once and for all the use of metal unblanketed atmospheres other than for comparison of colour indices or the calculation of bolometric corrections for Population II A-F spectral types. 相似文献
9.
In the open cluster NGC 752, 89 stars are observed in the Vilnius seven-colour photometric system, including probable members fainter than observed hitherto. Spectral classification of observed stars are made and individual reddening values are determined. The mean reddening of the cluster stars is equivalentE(B - V) = 0
.
m
025. By fitting on colour index-magnitude diagrams the cluster Main Sequence with the Hyades one the distance modulus (m - M)0 = 8
.
m
15 ± 0
.
m
15 is found. For 11 red giant members of the cluster absolute magnitudes are derived and compared with ones of the standard calibration. It is obtained that the cluster giants are in mean 0
.
m
6 fainter than giants of corresponding spectral class in the solar vicinity. 相似文献
10.
U, B, V photometry of the eclipsing binary DX Aqr has been presented for the first time. The period of the system comes out to be nearly half the period given by Strohmeier (1966) and a value of Od.472502 has been determined. The colour of the system has been discussed. The primary eclipse is a total occulation. The orbit seems to be eccentric. The system belongs to Algol type. DX Aqr may be a very complicated system. The present results are considerably different from those of earlier investigations. 相似文献
11.
Farouk M. Mahmoud 《Astrophysics and Space Science》1993,209(2):237-253
Sinusoidal variations in bothV - andB-bands were detected in some flare stars of the UV Ceti type outside of flares. This detection has confirmed the light variation detection in Johnson'sV -band in EV Lac at quiet-state luminosity by Pettersen (1980) with a cyclic period equals about 4
.
d
378 and an amplitude of about 0
.
m
07. An interpretation of these short cyclic periods is that they are due to intensity modulations from a photospheric spot group as a result of stellar equatorial rotations. A short period of 14 days with an amplitude of 0
.
m
099 was detected inB-band in AD Leo. For the two flare stars, BD+55° 1823 and DO Cep in bothV- andB-bands, cyclic periods of more than 3 days and less than 17 days with amplitudes more than 0
.
m
090 and less than 0
.
m
250 have been registered. A significant contribution has been found in the flare star EV Lac in bothV- andB-bands at its quiescent-state luminosity where the detected cyclic periods are agreed with that which was detected by Pettersen (1980) in the same flare star in Johnson'sV-band, about 4 days. Furthermore, we found the same cyclic period in the colour index,B - V (about 4 days) which strengthens starspot phenomenon. This colour index period could not be detected by Pettersen (1980). 相似文献
12.
M. Kuturaç C. Ibanoğlu Z. Tunca A. Y. Ertan S. Evren O. Tümer 《Astrophysics and Space Science》1981,77(2):325-346
The RS CVn-type eclipsing binary AR Lac has been observed in two colours,B andV, in 1978 and 1979. Several times of minima have been obtained during the observations and the new light elements have been calculated. The orbital period of the system was found to be decreasing with an amount of 14.6 s century–1.The light curves of the system obtained inB andV show a significant wave-like distortion outside eclipses. The amplitudes of the wave-like distortion inB andV are about 0
.
m
09 and 0
.
m
10 in 1978, and, 0
.
m
12 and 0
.
m
13 in 1979, respectively. The minima of the wave-like distortion have shifted with an amount of 0
.
p
40 in one year, thus indicating the migration period of the wave-like distortion is about 2.5 yr.A noticeable variation of light during the totality of primary minimum has also been observed. This variation can be attributed to the distortion wave which has been moving towards decreasing phases. 相似文献
13.
U, B, andV observations of AR Lacertae, obtained in 1981, have been presented alongwith the colour indices. A distortion wave minimum is found to lie at 0
.
P
21. The amplitude of the wave minimum inV filter is too weak, while it is stronger inU andV filters, the strongest being inV filter. The period of the migration wave turns out to be 2.53 yr. 相似文献
14.
U. S. Chaubey 《Astrophysics and Space Science》1982,81(1-2):283-293
The light curves of eclipsing binary DI Pegasi inU, B. andV filters have been presented and discussed. Photometric elements of the system have been determined. Using the colour indices, we estimate absolute dimensions and discuss the evolutionary status of the system. 相似文献
15.
Hiroyasu Ando 《Astrophysics and Space Science》1980,71(1):249-256
Preliminary study of the eclipsing binary AB Cas is presented here by using the photometric observational data. The primary component is one of the Sct variables with period of 0d.054, and whether the oscillation is of a radial mode or of a non-radial one is discussed. Two colour indices (B-V andU-B) data and the light curve analysis suggest that this binary system is a typical Algol type binary system, in which the primary component is near the ZAMS with about 2.3M
and the secondary one is a subgiant star with about 0.5M
. 相似文献
16.
Photoelectric zenith sky twilight brightness measurements have been carried out at Abu-Simbel site during spring season 1980 using blue, yellow and red filters. The results are reduced to deduce for the site the variation of the zenith sky twilight brightness in absolute units with sun's depression. The colour indices variation (B - V) and (B - R) with sun's depression are deduced from these results. Comparison is carried out between the present result and that deduced at Helwan and Daraw. 相似文献
17.
Analysis of the available observational data for the α-Persei cluster members shows that rotation effects on the intermediate-band
indices c1 and (u-b) are considerable. In c1, rotation produces a reddening of 0.040 magnitudes per 100 km s-1 In (u-b) the effect for B stars is found to be 0.06 magnitudes per 100 km s-1 ofV sin i.
The binaries and peculiar stars are found to behave differently in the colour excess (due to rotation) versusV sin i diagrams. These empirical effects can be utilised to recalibrate these colour indices and also to separate members
that are either chemically peculiar or in binary systems. 相似文献
18.
Z. Tunca 《Astrophysics and Space Science》1984,105(1):23-31
The RS CVn-type eclipsing binary SZ Psc was observed in two coloursB andV, in 1981. The rate of change of the period was calculated using two different least-squares procedures. The amplitudes of the light variations at outside eclipses are 0
.
m
181 and 0
.
m
213 inB andV colours, respectively. The light curves of the system have been solved using a new approximation. The radius of the cooler component is only 82% of its Roche-radius and the system is detached one. 相似文献
19.
UBV photoelectric photometry of the eclipsing binary system AW UMa has been presented. A slightly improved period of 0
.
d
4387304 has been given. The colour of the system has been discussed. Eccentricity is present in the system. Light and colour curves show that intrinsic light variations may be present in the system. The presence of mass transfer is a possibility. 相似文献
20.
The continuum energy distribution of the emission line star X Per (O9.5III-V) has been obtained in the wavelength range 340–710 nm and has been compared with the energy distribution of Cam in the same wavelength range. The continuum of the star is found to be modified by the circumstellar envelope. A number density of the order of 1011 in the envelope has been obtained from the observations of H in emission. 相似文献